<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" href="bootstrap-3.4.1/css/bootstrap.css">
    <link rel="stylesheet" href="css/index.css">
    <script type="text/javascript" src="js/jquery-3.4.1.min.js"></script>
    <script type="text/javascript" src="bootstrap-3.4.1/js/bootstrap.js"></script>

</head>
<body>
<!--导航栏-->
<div class="nav-content">
    <ul class="nav " >
        <li role="presentation" ><a href="#">首页</a></li>

        <li role="presentation" class="dropdown">
            <a class="dropdown-toggle" data-toggle="dropdown" href="#" role="button" aria-haspopup="true" aria-expanded="false">
                导航一 <span class="caret"></span>
            </a>
            <!--下拉栏-->
            <ul class="dropdown-menu">
                sss
            </ul>
        </li>

        <li role="presentation" class="dropdown">
            <a class="dropdown-toggle" data-toggle="dropdown" href="#" role="button" aria-haspopup="true" aria-expanded="false">
                导航一 <span class="caret"></span>
            </a>
            <ul class="dropdown-menu">
                sss
            </ul>
        </li>

        <li role="presentation" class="dropdown">
            <a class="dropdown-toggle" data-toggle="dropdown" href="#" role="button" aria-haspopup="true" aria-expanded="false">
                导航一 <span class="caret"></span>
            </a>
            <ul class="dropdown-menu">
                sss
            </ul>
        </li>

        <li role="presentation" class="dropdown">
            <a class="dropdown-toggle" data-toggle="dropdown" href="#" role="button" aria-haspopup="true" aria-expanded="false">
                导航一 <span class="caret"></span>
            </a>
            <ul class="dropdown-menu">
                sss
            </ul>
        </li>

    </ul>
</div>


</body>
</html>